Re: [Bier] BIER/IPv6 Requirements and Solutions

[Alvaro Retana <[e-mail]>]

On September 17, 2020 at 10:48:51 PM, Xiejingrong (Jingrong) wrote:

Jingrong:

Hi!

> The new requirements draft had been posted, please read and see if the
> direction is correctly followed and if your comments are addressed.

I'm replying because you continued this thread (and directed the
message to me), but I would have preferred a discussion inside the WG.

As Greg already mentioned, the requirements should provide enough
information to determine "what any proposed solution needs to address
that cannot be addressed with the available tools today".  In light of
my previous review, let's take a quick look at the mandatory
requirements:


[Line numbers from idnits.]

255	4.1.1.  Support various L2 link types

257	   The solution should support various kinds of L2 data link types.

Which are the mandatory types?  Ethernet, I guess.  I assume that
some, like maybe IEEE 802.15.4, may not be.

If the intent is to run BIER "through an IPv6 network underlay",
doesn't the requirement of multiple L2 link support fall on IPv6?


259	4.1.2.  Support BIER architecture

261	   The solution must support the BIER architecture.

263	   Supporting different multicast flow overlays, multiple sub-domains,
264	   multi-topologies, multiple sets, multiple Bit String Lengths, and
265	   deterministic ECMP are considered essential functions of BIER and
266	   need to be supported.

This is an obvious requirement.  Sure, the WG can discuss whether a
solution complies with the BIER architecture, but because we are in
the bier WG I would assume that is a given.

Are there specifics on how the sub-domains (for example) need to be
set up for an IPv6 network that may be different from an MPLS network?
 I’m just grasping at straws...


268	4.1.3.  Support deployment with Non-BFR routers

270	   The solution must support deployments with BIER-incapable routers.
271	   This is beneficial to the deployment of BIER, especially in early
272	   deployments when some routers do not support BIER forwarding but
273	   support IPv6 forwarding.

Support for non-BFR routers is already part of the architecture.


275	4.1.4.  Support OAM

277	   BIER OAM should be supported, either directly using existing methods,
278	   or by specifying a new method for the same functionality.  It may be
279	   considered essential as part of the BIER architecture in some cases.

As I mentioned before, there's no standard BIER OAM method to be
supported, or to build "a new method for the same functionality".


Assuming compliance with the BIER architecture, out of these mandatory
requirements I don't think I can identify one that would help the WG
decide whether a new solution is needed, or select between multiple of
them. :-(


Thanks!

Alvaro.